Sudden death has many causes and necropsy usually allows delineation of the specific cause. During the past 8 years we have studied at necropsy 6 patients, all man, who died suddenly outside the hospital and although necropsy disclosed cardiomegaly, a specific cause of death was not discernible. Certain clinical and morphologic features in these 6 patients are described. All 6 patients died outside the hospital. The most likely cause for the cardiomegaly in our 6 patients is systemic hypertension. Systemic arterial pressure was available in only 3 of the 6 patients and in each it was stated to have been elevated. None of the 6 patients had narrowing of any epicardial coronary artery, none had anatomic evidence of valvular, myocardial, congenital or pericardial heart disease. None had a coronary arterial anomaly. Cases of morbid obesity (less than 250 pounds) were excluded from this study. Although it is well recognized that patients with systemic hypertension have an increased frequency of both atrial and ventricular arrhythmias compared with normotensive persons and that hypertensive persons with left ventricular hypertrophy have a higher frequency of these arrhythmias compared with hypertensive persons without left ventricular hypertrophy, the occurrence of sudden death in persons with systemic hypertension in the absence of significant narrowing of 1 or more epicardial coronary arteries has not been described previously to our knowledge.